Machinability describes how easily a material cuts — the speed it tolerates, the finish it gives, and how hard it is on tools. This chart ranks common shop materials from easiest to hardest, with a typical carbide milling speed as a practical proxy.
| Material | Machinability | Carbide milling (SFM) | Notes |
|---|---|---|---|
| Aluminum 6061 / 2024 / 7075 | Excellent | 600 – 1200 | High speed, watch built-up edge |
| Brass (C360) | Excellent | 400 – 700 | Free-cutting, short chips |
| Delrin / acetal | Excellent | 600 – 1200 | Sharp tools, manage heat |
| Gray cast iron | Good | 200 – 400 | Abrasive dust, often run dry |
| Mild steel (1018, A36) | Good | 250 – 500 | Can be gummy annealed |
| Copper | Fair | 300 – 600 | Gummy, smears, needs sharp tools |
| Alloy steel (1045, 4140) | Fair | 200 – 400 | Slower, flood coolant |
| Tool steel A2 / D2 (annealed) | Fair to poor | 150 – 350 | Abrasive carbides, machine soft |
| Stainless 304 / 316 | Fair | 130 – 300 | Work-hardens, never dwell |
| Stainless 17-4 PH | Fair | 150 – 280 | Work-hardens, condition A |
| Titanium (Ti-6Al-4V) | Poor | 100 – 200 | Low speed, heavy coolant |
Rankings are approximate and depend on alloy, temper, and condition. Use the speed column as a starting point and tune from there.
For per-material detail see the machining data pages, and the full Feeds and Speeds Chart.